Say you want an introduction to atoms for kindergarten. Surely a first-tier professor of physics is sufficient expertise for this, no? And yet, not so much. For example, it's possible to see an atomic nucleus with your naked eye. But only because their are a couple of oddballs, that can be made to fluoresce visibly. The very good rule of thumb is "high energy, can't see". And that's the confident answer you'll get from many a first-tier chemist and physicist. To reliably learn of the exception, you need someone whose focus is nucleus dynamics. A tiny community. But unless you engage them, you won't know you can include a "this is real! see the glowing dot!" photo. I don't know of any non-visitors at MIT with that focus. So my not-quite joke is that MIT has insufficient domain expertise to write a truly excellent kindergarten intro to atoms. One would need to draw on expertise more broadly for that. (A more common failure mode is being able to field cross-domain questions like "does this story convey the right insights? what might a better one look like?")
So what might it take to pull together a massive breath of expertise to create content? The scale is daunting. A cell bio tome textbook publisher commented on their hundred+ authors, and I not-quite joked "great, and how many for the second page?".
Incentives for researchers are a challenge. But a VR intro cell biology project, pulling in researchers with direct expertise for interviews, reported a recurring problem... of getting them to stop and leave. So intrinsic motivations are significant.
Even recognition there's a need, let alone one worth funding, isn't well established.
And the collaborative tech infrastructure to make this possible... that's not a small endeavor.